Cube Overview
A cube is a multidimensional structure that provides a basis for developing Business Intelligence (BI) applications.
A cube consists of a set of measures and dimensions. For Microsoft Dynamics AX cubes, measures and dimensions are defined in the Application Object Tree (AOT). A perspective is used to identify the tables that contain the measures and dimensions.
Measures
A measure is a column in a table that contains quantifiable data, usually numeric, that can be aggregated. Measures correspond to something that users are interested in examining or analyzing, such as revenue, profit, or the total number of items sold. When you specify a measure, you must also specify an aggregate function that is used to aggregate the data. A cube has one or more measures.
Measures that you specify in Microsoft Dynamics AX are automatically grouped by their underlying tables into measure groups. For more information about measures and measure groups and how they are used in cubes, see Measures and Measure Groups (SQL Server 2005 Books Online). For information about defining measures in Microsoft Dynamics AX, see How to: Specify Measures for a Cube.
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When new measure groups are added to an existing cube, partitions are not automatically created for the measure groups during project update. If you want partitions for the new measure groups, you must manually create them. For more information, see Partitions (SQL Server 2005 Books Online). |
You can define measures at different levels and on different objects in the AOT using the Business Intelligence (BI) properties that appear in the Properties sheet. The following table describes where you can define measures and how they are used.
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Object |
Usage |
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Extended data type |
An extended data type, except when based on an enumeration, can be identified as a measure. When you identify an extended data type as a measure, any field that references the extended data type will be a measure unless overridden on the table field. An extended data type can extend another extended data type. If the base extended data type is a measure, you can either keep or override the settings from the base extended data type. |
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Table field |
You can identify a table field as a measure. If the table field is based on an extended data type that has already been identified as a measure, you can override the settings on the table field. There are two locations where you can identify a table field as a measure.
Property settings that are supplied on the perspective override the settings from all other locations. |
Dimensions
You can set AOT properties on tables and table fields to create analysis services dimensions and attributes. Attributes are table fields or columns in a table in the AOT. Dimensions are groups of attributes.
After you define dimension and attribute properties, you can add the dimension tables and table fields to a perspective to create a cube. If you do not want to specify dimensions and attributes directly on a table, you can create a perspective, add then add the dimension tables to the perspective. For more information, see How to: Create a Perspective for a Cube.
For more information about how dimensions are used in cubes, see Dimensions in SQL Server 2005 Books Online.
The relationships that are defined between dimensions and measure groups in a cube determine how the data in the cube is sliced. For Microsoft Dynamics AX cubes, relationships are automatically generated based on the relationships that exist between the tables in the application. When you open a BI project in SQL Server Business Development Studio (BIDS), you can view the relationships that were generated when you click the Dimension Usage tab in Cube Designer. You can define additional relationships or modify existing relationships between dimensions and measure groups in Cube Designer. For more information, see Dimension Relationships in SQL Server 2005 Books Online.
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By default, a key attribute of a measure group is the dataAreaId. In BIDS, if the granularity attribute and the key attribute are different attributes, then non-key attributes must be linked, directly or indirectly, to the granularity attribute. You can do this by specifying relationships between all other attributes and the attribute that is specified as the granularity attribute in the measure group. |
A partition is a container for measure group data. Partitions are used by Microsoft SQL Server Analysis Services to manage and store data and aggregations for a measure group in a cube. For more information, see Partitions (SQL Server 2005 Books Online).
A Key Performance Indicator (KPI) is a collection of calculations used to guage business success. A calculated member is a member of a dimension or measure group that is defined based on a combination of cube data, arithmetic operators, numbers, and functions. KPIs are added using Cube Desinger in BIDS after a project has been generated. The calculations that comprise a KPI are a combination of Multidimensional Expressions (MDX) and calculated members that are also added using Cube Designer. A KPI is generally comprised of the value achieved, a goal, a status value, and the trend.
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